A High Prevalence of Corrosion at the Head-Neck Taper with Contemporary Zimmer Non-Cemented Femoral Hip Components
- Brian J. McGrory, Johanna MacKenzie, George Babikian
- The Journal of Arthroplasty 30 (2015) 1265–1268
- Level of Evidence:
- None given
McGrory et al. analyzed a database for a single surgeon using 5 types of non-cemented femoral stems with metal-on-polyethylene (MoP) bearings of 32 and 36mm for the prevalence of failure for mechanically assisted crevice corrosion (MACC). They included only non-septic failures due to increasing or new pain, stiffness, and/ or limping in patients with cobalt ion levels of 1.6 ng/mL or greater. At a minimum follow-up time of 2 years, they identified 15 of 1’356 patients with adverse local tissue reactions (ALTR); a prevalence of 1.1%. At time of publication of this article 12 of those patients had undergone revision and the remaining 3 are awaiting revision. All revised cases had visible corrosion at the head-neck junction with soft tissue pathology of varying degrees. Time to presentation of symptoms was 3.7 years on average, and time to revision surgery was 1.6 years on average. X-rays showed some lytic lesions for 9 of the 15 patients. Soft tissue damage, including abductor muscle loss, was greatest in the 3 patients with the longest time to treatment (37–43 months) after presentation of symptoms.
Due to their findings the authors are concerned that once corrosion starts, soft tissue damage will follow and progress. They therefore recommend a prompt surgical intervention utilizing non-cobalt components once symptoms of MACC occur. McGrory et al. state that they cannot rule out the possible effect of genetic susceptibility or additive synergistic factors leading to adverse local tissue reactions (ALTR). However, since these clinical complications seem to be frequent, the authors express their concern regarding the general high number of THA surgeries performed worldwide and the possibly devastating and irreversible effect on soft tissue. Therefore, until the cause and prevention of MACC and ALTR is further understood, the authors recommend the use of ceramic (BIOLOX®delta) femoral heads.
- Study uses only the database of a single surgeon
- Study uses only one component manufacturer, although 5 stem types
- Inclusion criteria are random
- Authors’ opinion based on findings
- In this study the prevalence of MACC was 1.1–1.5%, with the majority of symptomatic patients already revised.
- All revised implants showed visible corrosion at the head-neck junction with varying degrees of soft tissue damage.
- If MACC symptoms (e.g. increasing or new pain) occur prompt surgical intervention is recommended to avoid severe soft tissue damage.
- The authors recommend the use of ceramic femoral heads with titanium stems until this problem is better understood.